Field of the Invention
The present invention relates to a position detection apparatus configured to detect a position of a movement body.
Description of Related Art
In a motorcycle, an accelerator grip is attached to a handlebar. A throttle valve provided to an internal combustion engine is operated to open and close as a driver turns the accelerator grip in the circumferential direction of the accelerator grip.
The opening and closing operation of the throttle valve needs to be controlled such that an amount of opening and closing of the throttle valve corresponds to an amount of turn (an amount of movement from an initial position) of the accelerator grip. Against this background, as a throttle opening detection apparatus, a position detection apparatus configured to detect the position of the accelerator grip is provided to the handlebar.
The position detection apparatus includes a rotor that rotates in conjunction with manipulation of the accelerator grip. As shown in FIGS. 2 and 4 of Japanese Patent Application Publication No. 2013-205141, the rotor is provided with multiple magnets. Thus, the multiple magnets change their positions while following the rotation of the rotor.
The position detection apparatus further includes a magnetic sensor formed from a Hall element or the like. The magnetic sensor, for example, detects directions (vectors) of magnetic fluxes of the magnets changing their positions, and outputs an electric signal corresponding to the vectors. Based on the electric signal, an amount of rotation (an angle of rotation) of the rotor, and accordingly the position of the accelerator grip are obtained.
It should be noted that an array of the three magnets shown in FIG. 4 of Japanese Patent Application Publication No. 2013-205141 is referred to as a Halbach array. In this case, magnetic fluxes concentrate on a side of the Halbach array, which faces the magnetic sensor, and the concentration accordingly increases magnetic force.